Document Generation: Table of Contents does not update

Thanks for looking into this!

Word doc and sample output are attached.

Data:

{
"customerName": "Kane Miller",
"customerVisits": 100,
"itemsBought": [
{
"name": "Sprays",
"quantity": 50,
"amount": 100
},
{
"name": "Chemicals",
"quantity": 100,
"amount": 200
}
],
"totalAmount": 300,
"previousBalance": 50,
"lastThreeBillings": [
100,
200,
300
],
"photograph": "data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAQAAAC1HAwCAAAAC0lEQVR42mP88h8AAu0B9XNPCQQAAAAASUVORK5CYII="
}